An investigation of the molecular and cellular mechanisms whereby C3H/10T 1/2 CL8 and 3T3 cells express multiple new differentiated phenotypes following 5-azacytidine treatment. This analog has been found to be incorporated into DNA and treated cultures show the development of functional striated muscle cells and biochemically differentiated adipocytes and chondrocytes. These phenotypes are being characterized in more detail and the cellular events involved in their appearance investigated. The ability of 5-azacytidine and other analogs of cytidine to inhibit DNA methylation are being determined since we have preliminary evidence suggesting that this inhibition is related to their mechanism of action.